Geologist Mark Tingay of the University of Adelaide told the BBC that Mount Agung now appears to be entering the next phase with a magmatic eruption, where the glow of lava is visible from the crater.

But he added that as eruptions are difficult to predict, it was “very hard to tell” how the situation would develop. “These eruptions can be quite large and extensive and violent, but this could also be a relatively minor eruption over time.”

He added that Indonesian authorities had made preparations for an eruption for months, and said they appeared “extremely well prepared”, with the situation “well under control”.

Should tourists be worried?

The main tourist stretch of Kuta and Seminyak is about 70km (43 miles) from the volcano, far beyond the exclusion zone.

But the ash prompted officials to shut down Bali’s Ngurah Rai airport from Monday to Tuesday morning.

Airport authorities said 445 flights had been cancelled, affecting 59,000 travellers, while Indonesia’s national hotel association said that stranded tourists staying at member hotels could stay one night for free.

The Australian government and the UK’s Foreign Office have advised travellers to be prepared for cancelled flights, closely monitor local media, and to heed local authorities’ warnings.

China (statement in Chinese) advised its citizens to be “cautious” if travelling to Bali.

The airport on neighbouring island Lombok reopened on Monday morning after it was shut briefly.

Image copyrightHolly Pelham

Image caption
Flights were cancelled at Ngurah Rai airport on Monday

How are locals coping?

Authorities have widened the exclusion zone to a 10km (6 mile) radius from the volcano, and have ordered people in the area to evacuate.

On Monday, officials said about 100,000 residents needed to leave, but so far only 40,000 have done so.

A spokesman for Indonesia’s disaster agency, Sutopo Purwo Nugroho, said that some people within the exclusion zone did not leave because the area was not touched the last time it erupted – more than 50 years ago.